Merge pull request #8544 from edolstra/handle-missing-gc-socket

LocalStore: :addTempRoot(): Handle ENOENT
(cherry picked from commit 7115edc85af060ef235ac0270245ab46cc828f7c)
Change-Id: Ie6b1596049c3fde09b98f2f0727899f98e48e6b1

1 files changed, 26 insertions, 12 deletions

diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index bbd57434d..6bcb069ba 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -2042,21 +2042,35 @@ void connect(int fd, const std::string & path)
     addr.sun_family = AF_UNIX;
 
     if (path.size() + 1 >= sizeof(addr.sun_path)) {
+        Pipe pipe;
+        pipe.create();
         Pid pid = startProcess([&]() {
-            Path dir = dirOf(path);
-            if (chdir(dir.c_str()) == -1)
-                throw SysError("chdir to '%s' failed", dir);
-            std::string base(baseNameOf(path));
-            if (base.size() + 1 >= sizeof(addr.sun_path))
-                throw Error("socket path '%s' is too long", base);
-            memcpy(addr.sun_path, base.c_str(), base.size() + 1);
-            if (connect(fd, (struct sockaddr *) &addr, sizeof(addr)) == -1)
-                throw SysError("cannot connect to socket at '%s'", path);
-            _exit(0);
+            try {
+                pipe.readSide.close();
+                Path dir = dirOf(path);
+                if (chdir(dir.c_str()) == -1)
+                    throw SysError("chdir to '%s' failed", dir);
+                std::string base(baseNameOf(path));
+                if (base.size() + 1 >= sizeof(addr.sun_path))
+                    throw Error("socket path '%s' is too long", base);
+                memcpy(addr.sun_path, base.c_str(), base.size() + 1);
+                if (connect(fd, (struct sockaddr *) &addr, sizeof(addr)) == -1)
+                    throw SysError("cannot connect to socket at '%s'", path);
+                writeFull(pipe.writeSide.get(), "0\n");
+            } catch (SysError & e) {
+                writeFull(pipe.writeSide.get(), fmt("%d\n", e.errNo));
+            } catch (...) {
+                writeFull(pipe.writeSide.get(), "-1\n");
+            }
         });
-        int status = pid.wait();
-        if (status != 0)
+        pipe.writeSide.close();
+        auto errNo = string2Int<int>(chomp(drainFD(pipe.readSide.get())));
+        if (!errNo || *errNo == -1)
             throw Error("cannot connect to socket at '%s'", path);
+        else if (*errNo > 0) {
+            errno = *errNo;
+            throw SysError("cannot connect to socket at '%s'", path);
+        }
     } else {
         memcpy(addr.sun_path, path.c_str(), path.size() + 1);
         if (connect(fd, (struct sockaddr *) &addr, sizeof(addr)) == -1)